Impeller for blowers



Jan. 3, 1933. F, v BURMAN 1,892,930

IMPELLER FOR LowERs Filed Feb. 3, 1930 I/mfeuor @Zim/g?! wumw" 557mHeimweg;

Patentedv dan. 3, 1933 ENT @FWQ FRANK V. BURMAN, OF ST. PAUL, MINNESOTAIMPELLER FOR BLOWERS Application led February 3, 1930.

This invention relates to fans or impellers and has for an object theprovision of a simple, highly ecient impeller which is perfectlybalanced and centered and which will opcrate noiselessly.

It is a further object of my present invention to provide an impeller ofthe type having a multiplicity of circumferentially arranged bladeswherein the body, fraine and ll@ blades are integrally formed andaccurately constructed from a single piece of material.

Most impellers used at the present time for Ventilating systems, oilburners and analogous uses have been objectionably noisy, due

l5 to the fact that the balance and centering have not been perfect.Casting of an integral impeller including the frame and blades has beenattempted and has been found entirely unsatisfactory, since the bladesand other portions will vary somewhat in thickness and consequently inweight. Many impellers comprise a frame or body and a multiplicity ofindependent blades rigidly attached to the body. it is practicallyimpossible in such structure to secure all the blades at the sameangulation and the same distance from the center, and it is usuallydifficult to perfectly center the hub with reference to the body.Moreover, independently attached impeller blades, in many instances,become detached from the body or frame of the impeller due to the effectof centrifugal force and are projected through the air with muchviolence, often causing considerable damage.

A further object of rn invention is to overcome the above noted ojections and to provide an impeller, the body and blades of which arepressed from a single sheet of material, whereby the device will beperfectly 0 centered and balanced and each blade identical in structureand angulation, since all blades are cut and pressed by the same die.

Another object is to provide a comparatively inexpensive and efficientimpeller ressed from a symmetrical pan-shaped ody, 'wherein the portionsof the body between the several pressed blades will beentirely'unobstructed to permit free passage of a1r.

Another object is to provide a simple effi- Serial No. 425,438.

cient method for making an integral irnpeller of the class abovedescribed.

These and other objects and advantages of the invention will be fullyset forth in the following description made in connection with theaccompanying drawing wherein like reference characters refer to similarparts throughout the several views` and wherein;

Fig. l is a front elevation of the intake of a blower having my impellermounted therein;

FigQQ'is-a vertical section taken on the line 2 2 of Fig'. i;

Fig. 3 is a detail View showing a fragment of the impeller in frontelevation;

Fig. 4.- is a fragmentary side elevation of my impeller detached, aportion of the reinforced and turned outer edge of thebody being brokenaway; and- Fig. 5 is a side elevation illustrating the step of mymethod, which consists in longitudinally slitting a symmetricalperfectly centered pan-shaped body.

As shown in the drawing, my impeller is mounted in a conventional blowercasing, comprising telescoped shell sections 5 and 6, said shellsections being constructed to afford a spiral passage surrounding theblower and terminating in a discharge 7. The shell sections 5 and 6 arerigidly secured to a base 8 by suitable means, such as a pair of anglebrackets 9 and 10, spot-welded or otherwise rigidly connected with base8 and with the exterior of the shells. Shell member 5 carries asymmetrical converging intake casing 11, which, as shown, is providedwith an outwardly projecting annular lip lla. A suitable electric motorM is mounted rear- 4wardly of the shell 6 and secured to base 8 by abracket 12, the armature shaft 13 of said motor being axiall alined withthe intake casing 11 and progecting within the center of the housingformed by shells 5 and 6. My impeller is fixed to armature shaft 13 anddisposed substantially centrally of the blower casing and concentricallywith the intake casing 11 and directly therebehind.

My impeller is constructed from a single sheet or disc of material, suchas sheet metal and the material is first pressed or spun to providedwith a perfectly centered circular hub-receiving aperture 14a and aseries of relatively small circumferentially spaced attachment apertures(as shown, four in number) surrounding said-hub-receiving aperture. Ifthe body is die-pressed, the base is preferably formed fiat by the dieand the hub-receiving aperture and attachment a ertures are preciselypositioned and forme by the die in the pressing operation.

The body so formed is next preferably placed on a spinner and the base14 is spun in the shape of a cone projecting inwardly toward theperipheral edge of the body. During the spinning operation, I alsoprefer to turn the edge of the body into a reinforcing bead X. -Itwill,of course, be understood that my lmethod is not limited to the stepof spinning the base or die-pressing the body,

but that the pan-shaped body may be formed from sheet material by anysuitable means whereby the body is perfectly balanced, symmetricallyformed and the hub-receiving aperture perfectly centered.

The pan-shaped body so formed is next progressively rotated and at eachrotative step a suitable die slits the body longitudinally from a pointadjacent its rim to a point adjacent its base and simultaneously pressesinwardly a relatively narrow portion of the stock to form one of theblades 15, the angulation of the blades being determined by the shape'ofthe die and the width of the blades being determined by timing andactuating mechanism for progressively rotating the .body before eachoperation of the die. 'llhe blades are of concave-convex cross sectionwith their concave sides disposed inwardly of the body and are so formedin the lstep of my method above described. In the steps of forming theblades, the material at the connected ends of the blades is'drawn by thedie so that it will not break or separate but will leave curved webs 15aand 15b at the ends of the blades. The material of the bod is onlysevered along straight lines exten ing longitudinally of the body andcircumferentlally` thereof. After the blades are slit and pressed out,the body may be progressively run through the die again to perfect theshaping of the blades and their inclination.

The portions of the body between two slits are skewed by the die orangled withrespect to the peripheral ed e of the body, and since theyare ressed an die-made each one will bea per ect replica of the other.

A hub is formed for thebody and is preferably made on a screw machine toinsure perfect symmetry, balance and centering. This hub includes aheavy sleeve which is provided with a" threaded radially extending Fromthe foregoing descri tion it will beseen that a very perfect impel ercan be made from sheet material at exceedingly low cost, and that theangulation of the multiplicity of blades, as well as the weight andshape of the blades, will be identical since the impeller is die formed.It further will beapparent that the impeller will be perfectly centered,and

consequently will operate eiliciently and practically noiselessly,` andcan never throw a blade.

One of the most important features of my invention is that the body ofthe impeller is comparatively unobstructed, thereby effecting thedisplacement of a relatively` great 'amount of air in comparison withother im`` pellers of the Sirocco type. It will be noticed that nomaterial of the vbody extends between the blades nor are the bladesprovided with any flanges or' other obstructions at their longitudinaledges. This is due to the fact that the blades are slit longitudinallfrom the material of the body and the sit portions turned on theirlongitudinal axes, the only connections of said blades with the'bodybeing the webs 15a and 15b at their extremities. As has been stated, thematerial of the bod is only severed along straight lines exten inglongitudinally thereof and the material is drawn at the ends and no ribor reinforcement member obstructing the passages between the 'blades isnecessary to support the y same. The passage of air radially andoutwardly of the impeller is only obstructed by the thickness of thesheet material, which is almost negligible.

Due to the structure and advantages above described, my impeller hasbeen found to have much greater capacity and eciency than othersheet-metal impellers -known to me at f this time.

It will, of course, be understood that va'- rious changes may be made inthe form, details, arrangementand proportions of the parts withoutdeparting from the scope of my invention. What is claimed is:

1. An impeller comprising a symmetrical lrim constructed of sheet metaland with a series of longitudinal slits intermediate its edges, theportions of said rim be tween said slits being bent out of the curvechannel in which a set screw is disposed for of said rim providingspaced blades connected rovided renee@ withA the rim only et their ends,the ende of the bent portions between seid longitudinal slits beinguncut and drawn in seid bending to form triangular-shaped ends for theblades angled with respect to the mein portions of the blades and bentout of the periphery ot the rim.

2. An impeller comprising e syetricel annular rim constructed of sheetmetal and provided with e series ot longitudinal slits intermediate itsends, the entire portions et the material of said rim between seid slitsFRANK V. BURR/MN.

